The objective of this study is to determine the efficacy of topical administration of delta 9 tetrahydrocannabinol (delta 9 THC), one of several cannabinoids found in marihuana, on the intraocular pressure (IOP) and blood pressure (BP) in subjects with increased IOP. Marihuana inhalation and oral delta 9 THC are effective in lowering IOP in humans with varying forms of glaucoma, although the cardivascular and central nervous system effects predominate at the dosages used. Delta 9 THC, administered topically in a light mineral oil vehicle, has been shown both safe and effective in lowering the IOP in dogs and in rabbits. We intend to determine the minimal effective dose of delta 9 THC on the IOP and to compare the effective doses of delta 9 THC with placebo in a double-blind study. Measurement of delta 9-THC plasma levels by radioimmuno-assays will allow correlation with IOP, BP and total outflow facility. Results of this study may aid in the development of a new drug for the treatment of glaucoma, still the leading cause of preventable blindness in the United States.